Yeah that's what I did. But if you've downloaded Wichu's sprite's you'll see that they're in the actual Pokemon numbering, not the internal rom numbering.
So what I did was renumber all the sprites starting after Celebi because if you pressed import all, the 25 empty slots would be replaced and so would the sprites after that, making a Pokemon have a sprite that doesn't belong to it.
So I took them out of their folders and started renaming them. For example,Treecko was #277 then so on and so on, with Chimecho ending with #411.
I still have all the sprites in a folder arranged by Generation, so if you needed them for any reason, I'd be happy to upload them to Rapidshare or a site like that for download, but it was actually an easy job. : )